雙主模型的Nginx高可用負載均衡集群

實驗目的：使用keepalived實現Nginx的雙主高可用負載均衡集群

實驗環境：兩臺Nginx proxy(雙主Nginx，各需要兩塊網卡，eth0連接內網，eth1連接外網)、兩臺web server(請求的負載均衡)、一臺client用于驗證結果。

注意：為了不影響實驗結果，在實驗開始前先關閉iptables和selinux

操作步驟：

一、配置IP

1.配置A主機的IP

# ip addr add dev eth0 192.168.10.2/24

2.配置B主機的IP

# ip addr add dev eth0 192.168.10.23/24

3.配置C主機的IP

# ip addr add dev eth0 192.168.10.3/24

4.配置D主機的IP

# ip addr add dev eth0 192.168.10.33/24

二、配置web服務(C和D主機都做同樣配置，只需修改默認主頁中的IP地址為本機的IP即可，以示區別)

1.安裝apache

# yum -y install apache

2.創建默認主頁

# vim /var/www/html/index.html

<h1>192.168.10.3</h1>

3.啟動apache

# service httpd start

三、配置sorry_server(此服務配置于Nginx proxy主機上，兩臺Nginx proxy都做同樣配置，只需修改默認主頁中的IP地址為本機的IP即可，以示區別)

1.安裝apache

# yum -y install apache

2.創建默認主頁

# vim /var/www/html/index.html

<h1>sorry_server:192.168.10.2</h1>

3.修改監聽端口為8080，以免與nginx所監聽的端口沖突

# vim /etc/httpd/conf/httpd.conf

Listen 8080

4.啟動apache服務

四、配置代理(兩臺Nginx proxy都做同樣配置)

1.安裝nginx

# yum -y install nginx

2.定義upstream集群組，在http{}段中定義；

# vim /etc/nginx/nginx.conf

        http {

            upstream websrvs {

                server 192.168.10.3:80;

                server 192.168.10.33:80;

                server 127.0.0.1:8080 backup;

            }

        }

3.調用定義的集群組，在server{}段的location{}段中調用；

# vim /etc/nginx/conf.d/default.conf

        server {

            location / {

                proxy_pass http://wersrvs;

                index index.html;

            }

        }

4.啟動服務

# service nginx start

五、配置keepalived

A主機上操作

1.安裝keepalived

# yum -y install keepalived

2.編輯A主機的配置文件/etc/keepalived/keepalived.conf，作如下配置：

! Configuration File for keepalived

    global_defs {

    notification_email {

        root@localhost

    }

    notification_email_from keepalived@localhost

    smtp_server 127.0.0.1

    smtp_connect_timeout 30

    router_id centos6

    vrrp_mcast_group4 224.0.100.39

    }

    vrrp_script chk_down {

        script “[[ -f /etc/keepalived/down ]] && exit 1 || exit 0”

        interval 1

        weight -5

    }

    vrrp_script chk_nginx {

        script “killall -0 nginx && exit 0 || exit 1”

        interval 1

        weight -5

        fall 2

        rise 1

    }

    vrrp_instance ngx {

        state MASTER

        interface eth1

        virtual_router_id 14

        priority 100

        advert_int 1

        authentication {

            auth_type PASS

            auth_pass MDQ41fTp

        }

        virtual_ipaddress {

            192.168.20.100/24 dev eth1

        }

        track_script {

            chk_down

            chk_nginx

        }

    }

    vrrp_instance ngx2 {

        state BACKUP

        interface eth1

        virtual_router_id 15

        priority 98

        advert_int 1

        authentication {

            auth_type PASS

            auth_pass XYZ41fTp

        }

        virtual_ipaddress {

            192.168.20.200/24 dev eth1

        }

        track_script {

            chk_down

        chk_nginx

        }

    }

B主機也作同樣配置，稍作修改即可，需要修改的地方如下：

    vrrp_instance ngx {

        state BACKUP

        priority 98

    }

    vrrp_instance ngx2 {

        state MASTER

        priority 100

    }

六、模擬故障，驗證結果

1.啟動兩臺Nginx proxy的keepalived服務

# service keepalived start

2.訪問192.168.20.100，結果應是后端的web server輪詢響應請求

3.訪問192.168.20.200，結果應是后端的web server輪詢響應請求

4.將后端的web server關閉一臺，訪問192.168.20.100或192.168.20.200，響應請求的將只是另一臺正常運行web server的主機

5.將后端的web server都關閉，此時訪問192.168.20.100或192.168.20.200，響應請求的將只是Nginx proxy中定義的主server中的sorry_server

6.關閉一臺Nginx proxy 的nginx服務，備server將把IP地址添加到本機，繼續提供服務，此時訪問192.168.20.100或192.168.20.200并不會有任何察覺